1. Field of Invention
The invention relates to a field emission display (FED), and more particularly to a field emission display with a triode structure.
2. Description of the Related Art
In a field emission display (FED), voltage is applied to a cathode and a gate electrode in a vacuum to supply an electric field for inducing electrons at the tip of a material, and then the field-emitted electrons left from the cathode plate are accelerated toward the anode (since positive voltage on the anode attracts) and collide with phosphors, thereby emitting luminescence.
Referring to FIG. 1, the FED has an anode plate 10 and a cathode plate 20 between which a vacuum cavity is formed. In the anode plate 10, an anode electrode layer 12 and a luminescent layer 13 are formed under a glass substrate 11 in order. In the cathode plate 20, a cathode electrode layer 22 is formed on a glass substrate 21, and a field-emitted array 23 having a two dimension distributions is disposed on the cathode electrode layer 22. On each array unit is disposed a gate layer 24 having a hole 25, inside which there is a metallic taper on the cathode electrode layer 22, and the gate layer 24 and the sides of the metallic taper are separated by an insulation layer 26. To achieve the array property of the above-mentioned structure, the structure needs to be implemented through expensive lithography and deposition, and the sizes of finished displays are seriously limited. Therefore, new materials and new processes have been developed.
As shown in FIG. 2, an FED disclosed in U.S. Pat. No. 6,359,383 not only utilizes a nanotube instead of a conventionally electronic emitter, but also provides a new structure of the FED. It includes an anode plate 30, a cathode plate 40 separated from the anode plate 30 at a distance and comprising a cathode electrode layer 41, a resistive layer 42 and a nanotube emitter 43, which is disposed on the top layer of the cathode plate 40 to perform the field emission in sequence, an insulation substrate 50 on which the cathode plate 40 is disposed, a gate layer 60 disposed at two sides of the nanotube emitter 43 on the cathode plate 40, and a dielectric substrate 70 separating the cathode plate 40 from the gate layer 60 to drive the nanotube emitter 43 for emitting electrons, thereby having lower requirements for driving voltage.
Although the structure of the FED provided in the prior art can be implemented through a simple thin film printing technique to reduce cost, a preferable solvent should exist to further reduce the driving voltage of the FED for accelerating the development of the driving system.